Male Anatomy MaleMale AnatomyAnatomy • Primary Organ – testes, genetically determined in mammals - testis releases hormones that then control the development of secondary sex characteristics - Secondary Organs – internal duct system • e.g., vas deferens, epididymus – external genitalia • Secondary Sexual Characters – e.g., antlers, coloration, facial hair Eutherian Mammal Testes • Paired and oval shaped • Shiny connective covering called the Tunica Albuginea • Divided into testicular lobules – Approximately 250 in human testis Seminiferous tubules (ST) • Each testicular lobule contains several coiled seminiferous tubules (ST) – ST site of sperm production • Each ST ~ 1.3 ft in humans • Total length of ST almost the length of a football field Testicular Histology Testis is made up of 2 major compartments 1) Region inside seminiferous tubules Spermatozoa development 2) Interstitial space outside ST - Leydig cells, - Androgen Production Seminiferous Tubules • Seminiferous tubules are lined by a germinal epithelium • Primary product is spermatozoa • Two cell types are found within ST – Germ cells – Sertoli cells Interstitial space • Outside the ST • Leydig cells – Responsible for androgen production in response to LH Blood testis barrier Limits fluid transfer between adluminal and basal and interstitial compartments Prevents gametes entering interstitial space Blood testis barrier 2 • The two compartments are separated by a blood testis barrier – Consists of a series of gap and tight junctions that serve as a physiological barrier separating the sertoli cells from the capillaries located in the interstitial space. – Function: prevents immune response to “foreign” protein of gametes • Sperm granuloma Ducts in males • All ducts in human males are derived from the primitive kidney – termed the Wolffian ducts • (or archinephric duct) Ducts in males 1) Seminiferous tubules – 2)Tubuli recti (straight tubules) 3) Rete testis- branched network of ducts 4) Vasa efferentia- carry to single common duct 5) Epididymis- single duct (>15 ft in human male) 6) Vas deferens pass out scrotum through inguinal canal to the urethra. Epididymis • Store sperm • Maturation of sperm Accessory Glands • Seminal Vessicles • Prostate gland • Bulbourethral glands • Involved in the production of semen Seminal Vesicles • Secrete alkaline, viscous fluid • High fructose content • Comprises the majority of semen Prostate Gland • Adds an alkaline solution to semen • Facilitates a favorable environment for sperm in the more acidic vagina and female reproductive tract • 13-33% of semen Bulbourethral Glands • Secrete lubricant Function of Ducts and Accessory Glands • Sperm transport • Sperm Storage • Sperm maturation • Production of semen Comparative testis anatomy • Paired (embryologically) in all species – Can be fused Shark Comparative testis anatomy • Paired (embryologically) in all species – Can be fused Birds - Ducts • sperm leave testes and enter epididymis – very small in the bird – not divided into three parts like mammals • then enter the ductus deferens – long narrow tube travels next to the ureter – ends at cloaca • psittacines (parrots) – sperm storage in the ductus deferens • passerines (finches, canaries, etc.) – sperm stored in the "seminal glomus" – convoluted structure at the end of the ductus.